The collection of leaves, grass clippings and other organic debris from lawn mowers into either fabric collector bags, or into rigid containers of metal or plastic, is well known.
However, in order to keep the air stream, and its attendant debris moving, means must be provided for venting the high-velocity air. In vacuum cleaners and lawnmowers which employ collector bags, this is commonly done by using a bag of porous weave which permits the air to perfuse through the fabric. However, as the bag fills up, the pores become clogged with debris which substantially blocks the air flow and greatly reduces the vacuum effect, sometimes reducing it to near zero. In addition, when such fabric bags become clogged, they are subjected to high internal pressure from the blower air stream. If the blower is very powerful, the bag can rip apart at the seams.
If the weave of the bag is made larger to avoid clogging, a great quantity of material is lost through the mesh, and the equipment operator may be exposed to quantities of choking dust and debris particles. Furthermore, the higher air pressure inside the bag tends to "plaster" the leaves, grass and other debris against the inside of the mesh, effectively blocking the air flow and reducing the vacuum effect.
In yet other types of lawn vacuum equipment, the collector container is made of rigid metal or plastic, or solid weave fabric which does not breathe at all thereby forming a substantially sealed chamber. In all such cases, either a clear opening or an open-mesh screen must be provided to vent the air, in order to provide the vacuum effect. These arrangements have just the same problems as described above. Either a great quantity of material is lost through the vent area, or the vent mesh itself clogs from the higher inside air pressure, which forces the debris against the vent screen, thus reducing or eliminating the vacuum effect.